The present invention relates generally to electronic devices for use with a refrigerator/freezer for dispensing ice cubes, and relates more specifically to an electronic device for use with a refrigerator/freezer for dispensing ice cubes where a power source is disconnected from a solenoid.
A common kitchen appliance is a refrigerator/freezer, and a common design for a refrigerator/freezer is one having side-by-side doors where a door on the right leads to a refrigerator, and a door on the left leads to a freezer. A premium refrigerator/freezer appliance of this type is one which includes both a water and ice cube dispenser. Usually, the water and ice cube dispenser is located on one of the doors, and is oftentimes on the left hand, or freezer-side, door. A typical water and ice cube dispenser used on a refrigerator/freezer is a dispenser which includes two cradles, one cradle for water and another for ice. In operation, when the cradle for ice is pressed, such as by a glass held by a person, a switch is engaged causing a solenoid to turn on. When the solenoid turns on, a door flap is opened, and an ice auger moves ice cubes along an ice chute, out the door flap, and into the glass. If delay circuitry were not provided in connection with the ice cube dispenser, when the glass is removed from the cradle (after the desired number of ice cubes have been received), the ice auger would instantly stop moving the ice cubes along the ice chute and the door flap would instantly close. Unfortunately, this instantaneous de-activation of the ice auger and closing of the door flap when the glass is removed from the cradle would often result in one or more ice cubes becoming stuck in the door flap, thus keeping the door flap propped open. Because the door flap essentially leads to the freezer, this propping open of the door flap may, if gone undetected for a long period of time, result in a large amount of cold air escaping from the freezer. This inevitably results in larger electric bills since more energy is needed to keep the freezer adequately cool. In more extreme situations, frost can build up in the freezer or general malfunctioning of the freezer may occur.
As a result, delay circuitry is often provided in connection with an ice cube dispenser. The delay circuitry operates to keep the door flap open for a period of time after the glass is removed from the cradle. In this manner, the final couple of ice cubes being moved along the ice chute by the ice auger are allowed to drop through the door flap, and no ice cubes become stuck in the door flap when the glass is removed from the cradle.
Prior art delay circuitry has comprised, for example, a charged capacitor connected to a Field Effect Transistor (FET), and the FET is connected to a solenoid. When a glass is removed from the cradle, the charged capacitor keeps the FET conducting until the capacitor runs out of energy. This arrangement has provided that the solenoid keeps the door flap open for a period of time after the glass is removed from the cradle. Unfortunately, this design provides that the FET is connected at all times to a power source, such as to a 120 Volt AC power line. As a result, a major electrical disturbance in the power line can cause the FET to fail, and cause the voltage to "punch through" the FET onto to the solenoid. Thereafter, the solenoid would remain powered whether or not the cradle is pressed. In fact, the solenoid would remain powered until the appliance were unplugged or until the solenoid overheats. Overheating of the solenoid can not only result in the freezer contents becoming ruined, but can result in material surrounding the solenoid, such as a plastic enclosure, melting and the dispenser generally being destroyed.
Therefore, prior art delay circuitry has solved some of the problems mentioned hereinabove, but some problems are still encountered. The present invention is directed to substantially eliminate the problems encountered heretofore.